Speed regulated oil delivery system

ABSTRACT

An exemplary oil delivery system comprises a dual pump system configured for reducing the buildup of pressure by unloading one or both pumps, thus reducing the buildup of heat within the hydraulic system. The dual pump system is configured for delivering oil in combination to a single hydraulic system or to two completely separate hydraulic systems. In addition, the oil delivery system can also be configured to unload one or both of the pumping sections at a pre-determined speed to again limit the flow to any existing open centered hydraulic system. As a result, the oil delivery system recirculates oil back to the reservoir and/or the inlet to the pump in the absence of a buildup of pressure, and thus an absence in the buildup of heat to conserve energy.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This is an application claiming priority from prior pending U.S.Provisional Application No. 601192,997, filed on Mar. 28, 2000.

FIELD OF THE INVENTION

[0002] The present invention relates to an oil delivery system. Moreparticularly, the present invention relates to speed regulated oildelivery system for use in mobile applications and the like, and whichcan provide, among other advantages, a reduced operating temperature,higher efficiency, reduced fuel consumption and an improved cycle time.

BACKGROUND OF THE INVENTION

[0003] In hydraulic systems, such as those used in various mobileapplications, excessive pump flow can cause undesirable heat buildupthat can result in damage to the hydraulic systems. This heat buildupproblem is more prevalent for applications which include a variablespeed input to the hydraulic pump, such as for open center-typehydraulic systems. For example, these variable speed pumps are typicallysized to run at lower revolutions per minute (RPM), such as 700 RPM, butthe hydraulic system must be able to operate with higher output flowduring a higher RPM range, such as 2100 RPM. Accordingly, by forcingadditional oil flow to the system at higher engine speeds, more pressureis required, which thus translates into additional heat buildup. Thus aneed exists for determining how to limit the amount of oil flow duringoperation of the hydraulic systems, such as during higher speeds.

[0004] Historically, the most frequently used method to limit flowcomprised the installation of a “dry valve” on the suction or inlet sideof the hydraulic pump. The dry valve is configured to operate such thatthe valve can effectively cut off the inlet flow of oil to the pump, andthus allow only a very small amount of oil to be pushed by atmosphericpressure into the inlet of the pump at a very high vacuum. This smallamount of oil is pushed through an orifice in the dry valve to lubricatethe pump. Unfortunately, this dry valve operation starves the inlet ofthe pump, thus causing cavitation and eventual pump failure.

[0005] In addition, another detriment to using the prior art dry valvesystem is the susceptibility to failure of the dry valve. For example,on occasions when the control valve or dry valve sticks in an actuatedposition, when a control valve is shifted downstream, or when the smallorifice of the dry valve becomes plugged, massive pump damage fromcavitation or lack of lubrication most often results in the hydraulicsystem.

[0006] An example of the shortcomings of the prior art systems can beseen in hydraulic systems utilized in large refuse or garbage vehicles.For present refuse vehicle hydraulic systems, the slow speed of movementof the arm or other lifting mechanism is undesirable for most vehicleoperators. Unfortunately as a result, instead of operating the engine inan “idle” status as designed, many operators frequently try to operatethe equipment at an increased engine speed such as by shifting theengine to neutral. This increase engine speed operation tends to openthe dry valve, and thus allows a full column of oil to go into the pumpof the hydraulic system. To prevent this high speed operation, manyhydraulic systems include a speed sensing control card for opening andclosing the inlet side of the pump. However, many operators have sincerealized that the speed sensing card is integrated into the controls ofthe hydraulic system via an electrical connector which can be easilybypassed or “jumpered”, thus eliminating the speed control for thehydraulic system. As a result, due to the operators increasing of theengine speed, excessive pump flow is created that leads to heat buildup.Moreover, the excessive pump flow and increased speed causes thehydraulic and mechanical equipment to operate in an overspeed conditionwhich results in premature wear and failure.

[0007] Accordingly, a need exists for an improved oil delivery systemthat addresses the problem of how to effectively limit or otherwiseregulate the amount of oil flow within a hydraulic system to preventheat buildup. In addition, a need exists for an improved oil deliverysystem with speed regulating features that addresses the problem of howto effectively limit or otherwise regulate the amount of oil flow tomechanical breakdown, such as that caused by operators increasing thepump flow of the hydraulic system in order to improve productivity ofthe equipment.

SUMMARY OF THE INVENTION

[0008] A speed regulated oil delivery system in accordance with thepresent invention addresses many of the shortcomings of the prior art.In accordance with one aspect of the present invention, an exemplary oildelivery system comprises a dual pump system configured for reducing thebuildup of pressure by unloading the flow of oil from one or both pumps,thus reducing the buildup of heat within the hydraulic system. Inaccordance with an exemplary embodiment, the dual pump system comprisesa first pumping section and a second pumping section, with each pumpingsection configured with an unloader valve.

[0009] In accordance with another aspect of the present invention, theoil delivery system can be configured to allow the combination of theflow of both pumping sections, at different flow rates and speeds, andunload one or both of the pumping sections at pre-determined speeds toagain limit the flow to any existing open centered hydraulic system. Asa result, the oil delivery system recirculates oil back to the reservoirand/or the inlet to the pumping sections without a buildup of pressure,and thus without the buildup of heat to enable the conservation ofenergy.

[0010] In accordance with another aspect of the present invention, theoil delivery system can also comprise a dual pump system configured fordelivering oil to two completely separate hydraulic systems, with eachpumping section configurable for different flow rates and speeds, andconfigured for unloading at similar or different pre-determined speeds.

[0011] In accordance with another aspect of the present invention, toprovide for the loading and unloading of a dual pump system through thecontrol of the unloader valves, the oil delivery system can suitablyinclude a control mechanism which can comprise many forms and which issuitably configured for determining the engine or pump speed, and thenproviding a control signal to suitably load or unload at least one ofvalves

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] A more complete understanding of the present invention may bederived by referring to the detailed description and claims whenconsidered in connection with the Figures, where like reference numbersrefer to similar elements throughout the Figures, and:

[0013]FIG. 1 illustrates a schematic diagram of an exemplary oildelivery system in accordance with the present invention;

[0014]FIGS. 2A through 2C illustrate exemplary embodiments of an oildelivery system configured for operating a hydraulic system;

[0015]FIGS. 3A through 3C illustrate exemplary embodiments of an oildelivery system as may be utilized to operate two separate hydraulicsystems; and

[0016]FIG. 4 is an exemplary embodiment of an unloader valve as may beconfigured with a pumping section.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION

[0017] The present invention is described herein in terms of varioushardware components and processing steps. It should be appreciated thatsuch components may be realized by any number of hardware componentsconfigured to perform the specified functions. For example, in itsvarious embodiments the present invention may include various hydraulic,pressure, and electronic components, e.g., pressure sensors, filters,valves, pumps, amplifiers, signal processing elements, solenoids, limitswitches and the like, which may carry out a variety of functions eitherdirectly or under the control of one or more microprocessors,programmable logic controllers or other control devices. In addition,those skilled in the art will appreciate that the present invention maybe practiced in any number of oil delivery contexts and that theillustrative embodiment described herein is merely one exemplaryapplication for the invention. For example, in addition to the exemplaryapplication with a hydraulic system for a refuse vehicle, the exemplaryoil delivery system may be suitably implemented into hydraulic systemsfor other mechanically functioning, hydraulically operated equipment andthe like. Further, it should be noted that the present invention may besuitably practiced within any variable speed, pressure or flowapplication, such as a variable speed engine, or a constant speed driveapplication with varying oil delivery requirements. Such generaltechniques that may be known to those skilled in the art are notdescribed in detail herein.

[0018] As discussed above, excessive pump flow during operation ofhydraulic systems causes several problems, including excessive heatbuildup. This can be readily understood by using the well-known formula:

[(flow rate×pressure)/(1714×pump efficiency)]=input horsepower,

[0019] Accordingly, by reducing either the flow rate (GPM) or thepressure (PSI), the input horsepower can be reduced, which is directlyproportional to the heat generated and the energy or fuel consumed.

[0020] In accordance with one aspect of the present invention, anexemplary oil delivery system comprises a dual pump system configuredfor reducing the buildup of pressure within the hydraulic system. Inaccordance with this aspect, the exemplary oil delivery system isconfigured for suitably addressing the pressure side or outlet of thedual pump system. For example, an exemplary oil delivery system mayinclude one or more unloader valves, such as ventable relief valves ortwo-way valves, configured for unloading one or both pumps, thusreducing the buildup of heat within the hydraulic system.

[0021] In accordance with an exemplary embodiment, with reference toFIG. 1, an exemplary oil delivery system 100 suitably comprises a pairof control valves 118 and 120, a filter 116 and a reservoir 110. Controlvalves 118 and 120 are configured to facilitate operation of variouscylinders or motors to permit operation of mechanical equipment, such asthe raising and lowering of the arm of a refuse truck. In accordancewith the exemplary embodiment, control valves 118 and 120 suitablycomprise open centered directional control valves; however, controlvalves 118 and 120 can comprise any other type of control valve. Filter116 suitably comprises any fluid conditioning mechanism, and can beconfigured for filtering, heating and/or cooling. In addition, filter116 can be suitably configured with any type of drain or outlet forproviding the fluid to reservoir tank 110. In the exemplary embodiment,filter 116 is configured as a return line filter. Meanwhile, reservoir110 suitably comprises any reservoir or tank configured for containingfluid, providing cooling or other like functions, such as a vented orpressurized tank, with the fluid being received above or below theexisting fluid level in tank. In accordance with an exemplaryembodiment, reservoir 110 comprises a vented reservoir, with the oilreturn below the oil level.

[0022] To facilitate operation of control valves 118 and 120, oildelivery system 100 suitably includes a dual pump system 101 configuredfor delivering oil to two completely separate systems, such as tocontrol valves 118 and 120. In addition, oil delivery system 100 mayalso include another fluid conditioning mechanism, such as a strainer114 configured between dual pump system 101 and reservoir 110. Stillfurther, oil delivery system 100 may also include a suction regenerationadapter configured for combining in a laminar like fashion the inlet ofdual pump system 101 with any return flow lines, such as those describedbelow. Regeneration adapter can comprise any configuration forfacilitating the reinjection or recirculating of oil back into the inletof dual pump system 101.

[0023] Dual pump system 101 suitably comprises a pair of pumpingsections 102 and 104, with pumping section 102 configured for operationwith control valve 118 and pumping section 104 configured for operationwith control valve 120. Pumping sections 102 and 104 can comprisevarious pump configuration and types. For example, pumping sections 102and 104 can be suitably configured in a double-vane type pumparrangement, or as gear pump or piston pump arrangements. In addition,pumping sections 102 and 104 can suitably comprise unidirectional orbidirectional type pumps, and fixed displacement or variabledisplacement type pumps. In accordance with the exemplary embodiment,for the purposes of illustration, pumping sections 102 and 104 suitablycomprise a pair of fixed displacement, unidirectional pumps. However, itis to be understood that any pumping configuration can be utilized, andthat these configurations will be referred to simply as “pumpingsections.”

[0024] To facilitate the reduction in pressure buildup within oildelivery system 100, pumping sections 102 and 104 can be suitablyconfigured with a pair of unloader valves 106 and 108 suitably coupledto the pressure side or outlet side of pumping sections 102 and 104.Unloader valves 106 and 108 can suitably comprise various types ofrelief valves or two-way valves, such as vented relief valves,proportional relief valves and the like. For example, unloader valves106 and 108 can suitably comprise solenoid vented relief valves,solenoid operated two-way valves, electrically proportional reliefvalves, or electrically proportional two way valves.

[0025] Unloader valves 106 and 108 are suitably configured forpermitting any oil discharged from the outlet of pumping sections 102and 104 to flow either through open center valves 118 and 120 to thehydraulic cylinders and motors, or through valve 106 and 108 back toreservoir tank 110 or the inlet of pumping sections 102 and 104 at verylow pressure. For example, unloader valve 106 can be suitably coupledbetween the outlet of pumping section 102 and the inlet of dual pumpsystem 101, such as by way of a regeneration adapter, or by othersuitable connection, while unloader valve 108 can be suitably coupledbetween the outlet of pumping section 104 and reservoir 110, such as byway of filter 116.

[0026] Accordingly, oil delivery system 100 can be configured to allowthe flow of oil from one or both pumping sections 102 and 104, even atdifferent flow rates and speeds, to the control valves 118 and 120, andthen suitably unload one or both of pumping sections 102 and 104 tolimit the flow. As a result, oil delivery system 100 can recirculate oilback to reservoir 110 and/or the inlet to pumping sections 102 and/or104 without a buildup of pressure, and thus without the buildup of heatto enable the conservation of energy.

[0027] As discussed above, one detriment of using the prior art dryvalve system is the high susceptibility to failure of the dry valvesduring operation. For example, on occasions when the control valve ordry valve sticks in an actuated position, when a control valve isshifted downstream, or when the small orifice of the dry valve becomesplugged, massive pump damage from cavitation or lack of lubrication mostoften results in the hydraulic system. However, through use of anexemplary dual pump system 101 within oil delivery system 100, if thecontrol valves 118 and 120 were to stick or lose power, the oil would besuitably directed through valves 106 and/or 108 back to reservoir tank110 or to the inlet of pumping sections 102 and/or 104, resulting in nodamage to the oil delivery system 100, or the mobile equipment.

[0028] The above exemplary embodiments provide an oil delivery system100 configured to allow the flow of oil from one or both pumpingsections 102 and 104, even at different flow rates and speeds, to thecontrol valves 118 and 120, and then suitably unload one or both ofpumping sections 102 and 104 to limit the flow. In accordance withanother aspect of the present invention, to determine when to suitablyunload one or both of pumping sections 102 and 104, oil delivery system100 can be configured to monitor, sense or otherwise observe the speedof operation of one or both of pumping sections 102 and 104; once thespeed of operation for the pumping section being monitored reaches athreshold level of speed, oil delivery system 100 can utilize unloadervalves 106 and 108 to unload the oil from one or both of pumpingsections 102 and 104. In accordance with another exemplary embodiment ofthe present invention, oil delivery system 100 can also be configured toallow the combination of the flow of both pumping sections 102 and 104and suitably unload one of the pumping sections at a pre-determinedspeed to again limit the flow to any existing open centered hydraulicsystem.

[0029] For illustration purposes, with reference to FIGS. 2A through 2C,an exemplary oil delivery system 200 comprising a dual pump system 101having, for example, equal sized pumping sections may be utilized incombination to supply oil to hydraulic systems 202 and 204, with eachsystem 202 and 204 having an operational requirement of oil flow of 30GPM at a speed of 725 RPM. In this example, the combined flow of dualpump system 101 is 30 GPM at a speed of 725 RPM, while at a higher speedof 1450 RPM, the combined flow increases to 60 GPM, i.e., with bothvalves 106 and 108 in a closed position as illustrated in FIG. 2A, thecombined flow of dual pump system 101 can range between 30 GPM and 60GPM at speeds between 725 RPM and 1450 RPM. Such a combination of flowfrom both pumping sections of dual pump system 101 may ideally beutilized at engine idle speeds, for example, at speeds between 600 RPMand 750 RPM, such as at 725 RPM.

[0030] If the control valves within hydraulic systems 202 and 204 arerated nominally at 40 GPM, it should be apparent that if the flow to thecontrol valves is not limited, additional pressure will be needed toforce the oil or other fluid through the valves, causing the developmentof additional heat and requiring significant additional fuelconsumption. However, by unloading at least one of the sections of thedual pump system 101 at higher speeds, the total flow can be suitablylimited to a level below the rating of the control valves. For example,with reference to FIG. 2B, if the speed of the dual pump systems exceedsthe idle speed threshold of 725 RPM, oil delivery system 100 can limitthe oil flow by unloading the oil flow through valve 106, i.e., the oilfrom pumping section 102. To prevent dual pump system 101 from“starving” for oil supply, unloader valve 106 can suitably unload theoil flow back to the inlet of dual pump system 101 to supplement the oilsupply. The remaining oil flow can be provided from pumping section 104to the hydraulic system. As a result, the total flow can be suitablylimited to 30 GPM, which is safely below the 40 GPM rating of thecontrol valves within hydraulic systems 202 and 204. Accordingly, byreducing the flow, the total horsepower can be suitably reduced, andthus the additional heat is not produced.

[0031] While FIG. 2B illustrates the opening of unloader valve 106 topermit the unloading of the oil flow to the inlet of dual pump system101, it should be noted that oil delivery system 200 could also besuitably configured to only open unloader valve 108 such that oil flowcould be directed to the reservoir tank 110. Furthermore, with referenceto FIG. 2C, both pumping sections within dual pump system 101 can beunloaded if desired, such as by the opening of unloader valves 106 and108 to permit the unloading of the oil flow to both the reservoir tank110 and to the inlet of dual pump system 101, with no oil being providedto control valves of the hydraulic systems. For example, unloader valve106 could be suitably opened at a low speed set-point or threshold, suchas at 725 RPM, while unloader valve 108 could be suitably opened at ahigher threshold, such as 1425 or 1800 RPM. As a result, both pumpingsections of dual pump system 101 could be unloaded at low pressure.

[0032] In addition, while the above illustration depicts the unloadingof oil flow through at least one of valves 106 and 108 to occur when thespeed of pumping sections 102 or 104 reaches a low or high RPM, itshould be noted that the unloading of oil flow could occur at variousother low or high speeds, for example, at any speed greater than thelower RPM, e.g., any speed greater than 725 RPM, or any speed less thanthe maximum RPM, e.g., any speed less than 2100 RPM. In other words, theunloading of oil flow through at least one of valves 106 and 108 can besuitably configured to occur when the total oil flow is safely below,approximate to, or exceeding the nominal rating of the control valves.

[0033] To provide for the loading and unloading of dual pump system 101through the control of valves 106 and 108, in accordance with anotheraspect of the present invention, oil delivery system 100 can suitablyinclude a control mechanism which can comprise many forms, for example,automatic or manual operation, and electrical, mechanical, orelectromechanical control. The control mechanism is suitably configuredfor determining the engine or pump speed, and then providing a controlsignal to suitably load or unload at least one of valves 106 and 108.

[0034] In accordance with an exemplary embodiment, oil delivery system100 may comprise a control mechanism configured for electricaloperation. In accordance with this embodiment, the electrically operatedcontrol mechanism can comprise a single input, dual adjustable outputdriver that is configured to sense the speed, e.g., the RPM, of theengine or pumping sections of dual pump system 101. Upon sensing thespeeds, the output driver can suitably provide two separate outputs orother control signals to load or unload one or both sections of dualpump system 101. In other words, the electronic output driver cansuitably determine the speed from the engines or pumps, and throughcontrol of the operation of valves 106 and 108, allow valves 106 and 108to suitably open to permit oil flow to reservoir 110, to providepressure and flow to the hydraulic systems, or to recirculate oil backto the inlet of dual pump system 101.

[0035] In accordance with an exemplary embodiment, the output drivercard can suitably provide a separate output signal to each of unloadervalves 106 and 108. For example, the output signal can comprise a powersignal to actively open unloader valve 106 and a power signal toactively open unloader valve 108. In addition, the output driver cardand unloader valves 106 and 108 could be configured such that a powersignal from the output driver card closes unloader valves 106 and 108,and eliminating the power signal opens unloader valves 106 and 108. Suchan arrangement could be very desirable if oil delivery system 101 losessystem power, which would result in unloader valves 106 and 108 suitablyopening to prevent or minimize any damage to the hydraulic system or thehydraulic cylinders and motors.

[0036] Moreover, the output driver card can be configured to unload dualpump system 101 at two or more different speeds, such as a at low speedof 700 RPM and at a high speed of 2000 RPM, or at various speeds inbetween. For example, the output driver card can be set to unload thefirst pumping section 102 at 1450 RPM, and to unload the second pumpingsection 104 at 1800 RPM. Thus for a hydraulic system that does not needto operate above 1800 RPM, pumping sections 102 and 104 can suitablyunload and recirculate oil back to reservoir tank 110 or to the inlet ofdual pump system 101 at a very low pressure.

[0037] In accordance with an exemplary embodiment, the electronic outputdriver can be configured on a control board or card for use with valves106 and 108. In addition, the output driver card can be configured foradjustment, for example adjustment of the speed settings for loading andunloading, through hardware mechanisms to permit operator adjustment.However, to prevent equipment operators from readily adjusting the speedlevels for activating the loading and unloading control signals, theadjustment of speed settings can be configured for software adjustmentonly. In addition, with reference to FIG. 4, the driver card and valves106 and 108 can be suitably configured on the same device and mountedonto dual pump system 101, or the output driver and valves 106 and 108can be separately mounted and connected.

[0038] Although the above exemplary embodiments disclose a dual pumpsystem 101 configured to pump oil into a single hydraulic system tooperate at a single speed, with reference to FIGS. 3A through 3C, oildelivery system 101 can also be configured for delivering oil to twocompletely separate systems 302 and 304. Moreover, when dual pump system101 is configured for operating on two completely separate systems, itmay be desirable for such a pumping configuration to be shut off atdifferent engine or pump speeds. Accordingly, if desired, oil deliverysystem 101 could be configured to unload pumping section 102 at a firstthreshold speed, e.g., as illustrated in FIG. 3B, and to unload pumpingsection 104 at a second threshold speed, e.g., as illustrated in FIG.3C, allowing the oil to be recirculated through the reservoir tank 110and/or the inlet of pumping sections 102 and 104. Accordingly, sincethis recirculation of the oil through reservoir 110 does not require anyadditional pressure, no additional heat is produced, i.e., heat isdissipated, not generated, and fuel is conserved.

[0039] As a result, several major advantages of the speed regulated oildelivery system over the prior art can include a reduction in operatingtemperature, an increase in productivity and reliability, a higherefficiency and a reduction in fuel consumption, an decrease in cycletime, and a significantly quieter system overall. Still further, the oildelivery system can allow an operator to operate the hydraulic systemand equipment “in gear” at engine idle speeds, and can allow the use ofvane type pumps which are not readily compatible with prior art dryvalve systems.

[0040] The present invention has been described above with reference toan exemplary embodiment. However, changes and modifications may be madeto the exemplary embodiment without departing from the scope of thepresent invention. In addition, the various components of the oildelivery system may be implemented in alternate ways depending upon theparticular application or in consideration of any number of designfunctions associated with the operation of the system. For example,although not described in detail above, the control device of the oildelivery system can be suitably driven by any device for providing anelectrical control signal, such as a switch, PLC, microprocessor,pressure switch, limit switch, or other like means for supplying acontrolled voltage or amperage to the control device. In addition,although only two pumps and control valves are shown and describedabove, an exemplary oil delivery system could be readily configured withany number of pumps and valves, all configured with a single or separatecontrol device to operate and unload at any number of speeds or flowrates. In addition, although vented relief or two-way valves are shownabove, the system can also be readily configured using soft shift,spool-type valves or electronically proportional relief valves to unloadthe pumps to the reservoir or the inlet to the pumps, thus eliminatingdecompression and the resulting pressure shock to the hydraulic system.These and other changes or modifications are intended to be includedwithin the scope of the present invention.

1. An oil delivery system configured to prevent heat buildup in a hydraulic system, said oil delivery system comprising: a reservoir tank for the storing of a hydraulic fluid; a dual pump system comprising a first pumping section and a second pumping section, each of said first pumping section and said second pumping section having an outlet configured for coupling to a control valve of the hydraulic system; a pair of unloader valves comprising a first valve and a second valve, said first valve being coupled between said outlet of said first pumping section and an inlet to said dual pump system, said second valve being coupled between said outlet of said second pumping section and said reservoir tank; and wherein said oil delivery system is configured to limit the amount of oil flow to the hydraulic system below a threshold level of oil flow by using speed regulation to determine when to recirculate the hydraulic fluid from at least one of said first pumping section and said second pumping section through at least one of said pair of unloader valves.
 2. The oil delivery system of claim 1 , wherein said oil delivery system is configured to limit the amount of oil flow to the hydraulic system below a threshold level of oil flow by determining the speed of operation for at least one of said first pumping section and said second pumping section, and then recirculating the hydraulic fluid when a threshold level of speed has been obtained by said at least one of said first pumping section and said second pumping section.
 3. The oil delivery system of claim 2 , wherein said oil delivery system is configured to recirculate the hydraulic fluid from at least one of said first pumping section and said second pumping section through at least one of said pair of unloader valves when a control valve of the hydraulic system becomes inoperable.
 4. The oil delivery system of claim 2 , wherein said oil delivery system is configured to recirculate the hydraulic fluid from at least one of said first pumping section and said second pumping section through at least one of said pair of unloader valves when said threshold level of speed is greater than 725 RPM.
 5. The oil delivery system of claim 4 , wherein said oil delivery system is configured to recirculate the hydraulic fluid from at least one of said first pumping section and said second pumping section through at least one of said pair of unloader valves when said threshold level of speed is greater than 1450 RPM.
 6. The oil delivery system of claim 2 , wherein said oil delivery system is configured to recirculate the hydraulic fluid from both said first pumping section and said second pumping section.
 7. The oil delivery system of claim 6 , wherein said oil delivery system is configured to recirculate the hydraulic fluid from said first pumping section at a first threshold level of speed and from said second pumping section at a second threshold level of speed.
 8. The oil delivery system of claim 7 , wherein said oil delivery system is configured to recirculate the hydraulic fluid from said first pumping section at a speed of at least 700 PPM and from said second pumping section at a speed of at least 1400 PPM.
 9. The oil delivery system of claim 2 , wherein said oil delivery system further comprises a control mechanism configured for sensing said speed of operation for at least one of said first pumping section and said second pumping section, and then providing at least one output control signal to said at least one of said pair of unloader valves to facilitate recirculation of the hydraulic fluid when a threshold level of speed has been obtained by said at least one of said first pumping section and said second pumping section.
 10. The oil delivery system of claim 9 , wherein said control mechanism is configured to facilitate recirculation of the hydraulic fluid at different threshold levels of speed for said first pumping section and said second pumping section.
 11. The oil delivery system of claim 9 , wherein said control mechanism comprises an electrically operated, single input, dual adjustable output driver card.
 12. The oil delivery system of claim 9 , wherein said control mechanism is configured such that said threshold level of speed can only be adjusted through software adjustment.
 13. The oil delivery system of claim 2 , wherein said dual pump system comprises a double-vane type pumping configuration.
 14. The oil delivery system of claim 2 , wherein said dual pump system comprises a pair of fixed displacement, unidirectional type pumping configurations.
 15. The oil delivery system of claim 13 , wherein said first pumping section and said second pumping section are configured to operate at different speeds at the same time and to provide oil flow to two separate hydraulic systems.
 16. The oil delivery system of claim 2 , wherein said pair of unloader valves comprise at least one of a solenoid vented relief valve and an electrically proportional relief valve.
 17. The oil delivery system of claim 2 , wherein said pair of unloader valves comprise at least one of a solenoid operated two-way valve and an electrically proportional two-way valve.
 18. A hydraulic system for providing hydraulic power for operation of mobile equipment, the hydraulic system comprising: a pair of control valves for providing directional control of oil flow to hydraulic cylinders used in the operation of the mobile equipment; a reservoir tank for the storing of hydraulic oil; a filter coupled between said pair of control valves and said reservoir tank, said filter configured for conditioning of the hydraulic oil; a dual pump system comprising a first pumping section and a second pumping section, each of said first pumping section and said second pumping section having an outlet configured for coupling to at least one of said pair of control valves; a pair of unloader valves comprising a first valve and a second valve, said first valve being coupled between said outlet of said first pumping section and an inlet to said dual pump system, said second valve being coupled between said outlet of said second pumping section and said reservoir tank; and a control mechanism for controlling operation of said pair of unloader valves; wherein said oil delivery system is configured to limit the amount of oil flow to the hydraulic system below a threshold level of oil flow by using speed regulation to determine when to recirculate the hydraulic fluid from at least one of said first pumping section and said second pumping section through at least one of said pair of unloader valves.
 19. The oil delivery system of claim 18 , wherein said oil delivery system is configured to limit the amount of oil flow to the hydraulic system below a threshold level of oil flow by using said control mechanism for determining the speed of operation for at least one of said first pumping section and said second pumping section, and then recirculating the hydraulic fluid when a threshold level of speed has been obtained by said at least one of said first pumping section and said second pumping section.
 20. The oil delivery system of claim 19 , wherein said oil delivery system is configured to recirculate the hydraulic fluid from at least one of said first pumping section and said second pumping section through at least one of said pair of valves when said threshold level of speed is greater than 1450 RPM.
 21. The oil delivery system of claim 20 , wherein said oil delivery system is configured to recirculate the hydraulic fluid from both said first pumping section and said second pumping section.
 22. The oil delivery system of claim 21 , wherein said oil delivery system is configured to recirculate the hydraulic fluid from said first pumping section at a first threshold level of speed and from said second pumping section at a second threshold level of speed.
 23. The oil delivery system of claim 19 , wherein said control mechanism is configured for sensing said speed of operation for at least one of said first pumping section and said second pumping section, and then providing at least one output control signal to said at least one of said pair of unloader valves to facilitate recirculation of the hydraulic fluid when a threshold level of speed has been obtained by said at least one of said first pumping section and said second pumping section.
 24. The oil delivery system of claim 23 , wherein said control mechanism is configured to facilitate recirculation of the hydraulic fluid at different threshold levels of speed for said first pumping section and said second pumping section.
 25. The oil delivery system of claim 19 , wherein said first pumping section and said second pumping section are configured to operate at different speeds at the same time.
 26. A oil delivery system configured to minimize the overheating of a hydraulic system, said oil delivery system comprising: a reservoir tank for the storing of a hydraulic fluid; a dual pump system comprising a fixed-displacement type pumping configuration including a first pumping section and a second pumping section, each of said first pumping section and said second pumping section having an outlet configured for coupling to a control valve of the hydraulic system; a pair of unloader valves comprising a first unloader valve and a unloader second valve, said first unloader valve being coupled between said outlet of said first pumping section and an inlet to said dual pump system, said second unloader valve being coupled between said outlet of said second pumping section and said reservoir tank; and a control mechanism for controlling operation of said pair of unloader valves, said control mechanism being configured for sensing a speed of operation for at least one of said first pumping section and said second pumping section, and then for providing at least one output control signal to said at least one of said pair of unloader valves to facilitate recirculation of the hydraulic fluid when a threshold level of speed has been obtained by said at least one of said first pumping section and said second pumping section such that said oil delivery system is capable of limiting the amount of oil flow to the hydraulic system to minimizing the overheating of the hydraulic system.
 27. The oil delivery system of claim 26 , wherein said oil delivery system is configured to recirculate the hydraulic fluid from at least one of said first pumping section and said second pumping section through at least one of said pair of unloader valves when a control valve of the hydraulic system becomes inoperable.
 28. The oil delivery system of claim 26 , wherein said oil delivery system is configured to recirculate the hydraulic fluid from at least one of said first pumping section and said second pumping section through at least one of said pair of unloader valves when said threshold level of speed is greater than 1450 RPM.
 29. The oil delivery system of claim 26 , wherein said oil delivery system is configured to recirculate the hydraulic fluid from both said first pumping section and said second pumping section, with the hydraulic fluid being recirculated from said first pumping section at a first threshold level of speed and from said second pumping section at a second threshold level of speed.
 30. The oil delivery system of claim 26 , wherein said control mechanism is configured to facilitate recirculation of the hydraulic fluid at different threshold levels of speed for said first pumping section and said second pumping section.
 31. The oil delivery system of claim 30 , wherein said control mechanism is configured such that said threshold level of speed can only be adjusted through software adjustment.
 32. The oil delivery system of claim 13 , wherein said first pumping section and said second pumping section are configured to operate at different speeds at the same time. 